1. Field of the Invention
The present invention relates to a system for processing a color image and, more particularly, to a color image processing system in which image data is input to obtain a color image.
2. Description of the Related Art
In connection with the increase in use of digital color copying machines in recent years, there has been marketed a type of system which is connected to a computer and outputs CG and line images produced by the computer, or outputs of natural images which have been read by a scanner and then input to the computer. In such a system, to provide an interface between the computer and copying machine, the computer is connected to the copying machine through an interface unit (hereinafter referred to as an IU) having a memory. In many cases, the memory has a storage for storing multi-value data, such as natural images, and another storage for storing binary data, such as characters and line images, thus making it easy to handle the multi-value data and binary data processed by the computer. A multi-value image signal line and binary image signal line are separately placed between the copying machine and the IU so that both components can optimally process images. In this type of system, it is natural that characters and line images edited by the computer are colored and then printed out. In such a case, it is impossible to color the characters and line images on the basis of only data transmitted through the binary image signal line. Therefore, the copying machine first receives information on colors and a color zone so as to color the binary image data, and then a binary image signal to process it. The same binary image data is transmitted from the IU to the copying machine color plane by color plane because of the above process and because, when the binary image data and image data read by the scanner of the copying machine are superimposed on each other, printing of the image information in a zone assigned to the binary image data is prohibited.
Because of an increase in the demand for presentation, there have been a number of apparatuses used as so-called DTP systems, in which a PDL, such as Post Script (hereinafter referred to as PS) of Adobe Company, is used to output color characters and line images composed of binary data.
Also in the above system, in the same manner as described above, to provide an interface between a computer and a copying machine, these components are connected to each other through an interface unit (hereinafter called a PS-IU) having a memory. The PS from the computer is converted into a raster image by an interpreter in the PS-IU and then transmitted to the copying machine as a binary signal. In such a case, unlike in the case of the IU mentioned previously where the same binary image data is transmitted color plane by color plane, binary image data corresponding to the coloring material of each plane is transmitted from the PS-IU to the copying machine.
However, in each of the system types mentioned above, the structure of binary image data processed by the computer differs from that of binary image data processed by the copying machine. For this reason, if data transmitted from both the computer and the copying machine is processed by, for example, the copying machine, an interface used for the IU or PS-IU must be provided in the copying machine. In addition, software for controlling the sequence of the operation of the interface must be changed, thus making the structure of the copying machine complicated.
In the above-mentioned DTP system, the copying machine converts binary image data, transmitted through the PS-IU in accordance with the coloring material of each color plane, into fixed multi-value image data. It is therefore impossible to change the density and color of the binary image data.
In the above-noted known DTP system, of course, the color balance and the density key of the copying machine are capable of changing the color and density. However, once such change has been made, the color and density cannot be changed again even during normal printing. The color and density must therefore be readjusted every time a printing operation is performed. Also, when multi-value images, such as natural images, and binary images in the PDL are printed on the same recording paper, adjustment by the color balance to the color and density of the binary images adversely affects the color and density of the multi-value images.
As described previously, in the case of the IU, since the copying machine first receives information on color used for the binary image data, the computer is capable of adjusting the color and density of the binary image data. However, if the color and density are adjusted by the color balance and the density key of the copying machine, it is impossible to obtain the desired color and density.
The present invention solves the above-mentioned problems simultaneously or one by one.
An object of this invention is to provide an image processing system capable of connecting a type of image processing unit to another type of image processing unit.
Another object of this invention is to provide an image processing system capable of connecting a type of image processing unit to another type of image processing unit and changing the color and density of an image when the image is formed.
To achieve the above objects, this invention provides an image processing system which comprises setting means for setting density data, first processing means for processing first image data in accordance with first density data set by the setting means, second processing means for processing second image data in accordance with second density data set by the setting means and information on the formation of an image composed of the second image data, synthesizing means for synthesizing the first image data output from the first processing means and the second image data output from the second processing means, and forming means for forming an image based on image data output from the synthesizing means.
A further object is to provide a color image processing apparatus constituting the above image processing system which achieves the above objects.
Yet another object is to provide a novel interface used for the above image processing system which achieves the above objects.
Other objects, features and advantages of this invention will become more fully apparent from the following detailed description of the preferred embodiments taken in connection with the accompanying drawings.